Systems and methods for wireless signal measurement and reporting for device-to-device communication

ABSTRACT

Methods, systems, and devices for configuration and reporting of proximity detection measurements are disclosed herein. User equipment (UE) is configured to receive and store a PD-RS list from an evolved universal terrestrial radio access network (E-UTRAN) node B (eNB). The PD-RS list includes a radio resource configuration for at least a first proximity discovery reference signal (PD-RS). The UE is configured to measure at least the first PD-RS to determine a signal parameter for the first PD-RS. The UE reports the signal parameter for the first PD-RS to the eNB.

RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Application No. 61/707,784, filed Sep. 28, 2012, which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to wireless signal measurement andreporting for device-to-device communication in a wireless communicationnetwork.

BACKGROUND

Wireless mobile communication technology uses various standards andprotocols to transmit data between a base station and a wireless mobiledevice. Wireless communication system standards and protocols caninclude the 3rd Generation Partnership Project (3GPP) long termevolution (LTE) standard; the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16 standard, which is commonly known to industrygroups as WiMAX (Worldwide Interoperability for Microwave Access); andthe IEEE 802.11 standard, which is commonly known to industry groups asWiFi. In 3GPP LTE systems the radio access network (RAN) known asEvolved Universal Terrestrial Radio Access Network (E-UTRAN) includesthe base station (also commonly denoted as E-UTRAN NodeB, eNodeB, oreNB), which communicate with a wireless communication device, known asuser equipment (UE).

Proximity-based discovery and device-to-device (D2D) communicationbetween devices (such as UEs) have gained strong interest because theyprovide the network operator the possibility to offer new types ofapplications and services for commercial, social, and public safety use.Furthermore, proximity-based discovery and D2D communication provide thenetwork operator the possibility to temporarily offload user trafficexchanged between two UEs in proximity of each other from the networkinfrastructure to a D2D direct communication path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a communication system forUE-assisted proximity discovery consistent with embodiments disclosedherein.

FIG. 2 is a schematic block diagram illustrating UE and eNBcommunicating to configure proximity measurement and reportingconsistent with embodiments disclosed herein.

FIG. 3 is a diagram of a communication message flow illustratingcommunication between a UE and an eNB to configure, measure, and reportproximity detection measurements consistent with embodiments disclosedherein.

FIG. 4 is a table illustrating example measurement gap patternsconsistent with embodiments disclosed herein.

FIG. 5 is a graph illustrating a signal parameter exceeding an absolutethreshold consistent with embodiments disclosed herein.

FIG. 6 is a graph illustrating a signal parameter falling below anabsolute threshold consistent with embodiments disclosed herein.

FIG. 7 is a graph illustrating signal parameters for multiple discoverysignals exceeding an absolute threshold consistent with embodimentsdisclosed herein.

FIG. 8 is a graph illustrating a signal parameter improving above acorresponding signal parameter for a reference signal consistent withembodiments disclosed herein.

FIG. 9 is a diagram of a communication message flow illustratingcommunication between a UE, an eNB, and proximity UEs to configure,measure, and report proximity detection measurements consistent withembodiments disclosed herein.

FIG. 10 is a schematic diagram of a mobile device consistent withembodiments disclosed herein.

DESCRIPTION OF EMBODIMENTS

A detailed description of systems and methods consistent withembodiments of the present disclosure is provided below. While severalembodiments are described, it should be understood that disclosure isnot limited to any one embodiment, but instead encompasses numerousalternatives, modifications, and equivalents. In addition, whilenumerous specific details are set forth in the following description inorder to provide a thorough understanding of the embodiments disclosedherein, some embodiments can be practiced without some or all of thesedetails. Moreover, for the purpose of clarity, certain technicalmaterial that is known in the related art has not been described indetail in order to avoid unnecessarily obscuring the disclosure.

There are two basic approaches for proximity discovery for UEs includingUE-based discovery and UE-assisted discovery. In UE-based proximitydiscovery, the UE measures the proximity discovery signals transmittedfrom other UEs to be discovered, and determines on its own which ofthose UEs are within its proximity. In UE-assisted proximity discovery,the UE measures the proximity discovery signals transmitted from otherUEs and sends the measured results to the network. UE-assisted proximitydiscovery allows the network to control device-to-device communicationaccording to its own policies and can thus optimize the function andusage for the network and also maintain security for UEs. Networkcontrol is also useful when licensed bands are being used for D2D directcommunication, such as in LTE direct. The present disclosure focuses onUE-assisted proximity discovery including, for example, configuration ofUEs for signal measurement and reporting to the network.

An objective of 3GPP standard development organization (SDO) discussionsis to study use cases and identify potential requirements for operatornetwork controlled discovery and communications between devices that arein proximity, under continuous network control, and are under LTEnetwork coverage. In this context a new type of UE and network is beingconsidered that supports discovery and communications between devicesthat are in proximity. A UE and a network that implement these proximityservices may be referred to as a D2D-enabled UE and a D2D-enablednetwork, respectively.

As used herein, the terms proximity discovery and proximity-baseddiscovery are given to mean a process that identifies a device or UEthat is in proximity to another UE. The term open proximity discovery isgiven to mean proximity discovery without explicit permission from theUE being discovered. The term restricted proximity discovery is given tomean a proximity discovery that takes place with permission from the UEbeing discovered. The term D2D communication is given to mean acommunication between at least two or more UEs in proximity by means ofa direct communication path established between the UEs. Examples ofdirect communication paths for D2D communication include LTE direct,WiFi direct, Bluetooth, or other direct communication path protocols orstandards.

In a D2D-enabled network and/or with D2D-enabled UEs, proximitydiscovery may have different requirements based on whether or not a UEis currently engaged in D2D communication. For example, proximitydetection while the UE is engaged in D2D communication may be used todetermine whether another UE continues to remain in close enoughproximity to continue the D2D communication. If the UE is not yetengaged in D2D communication, proximity detection may be used todetermine whether another UE is close enough to the UE to establish aD2D session. In the live D2D communication situation, proximity may needto be detected on a frequent interval or even continuously to make surethat data can be communicated or so that a data flow may be switched toan infrastructure path before the UEs move too far apart. If the UE isnot engaged in D2D communication, less frequent checks or even a singlecheck for proximity may suffice.

According to one embodiment, proximity discovery is performed based onmeasurements of a reference signal made by a UE. For example, the UE maymeasure one or more reference signals from a UE or other device. In oneembodiment, the results of these measurements are forwarded to thenetwork (eNB and/or core network entity) to determine whether other UEsare in proximity of the reporting UE. According to one embodiment, thesignals measured are UE-specific. For example, the UE measures thesignals transmitted from other UEs instead of signals from a servingcell or a neighbor cell. The UE may measure any type of reference signalfor proximity discovery. For example, an LTE uplink signal such as asounding reference signal (SRS) can be used or another proximitydetection or D2D-specific signal may be used. As used herein the termproximity discovery reference signal (PD-RS) is given to genericallymean any signal used as a reference signal for proximity discovery of anearby device, such as a UE.

In one embodiment, different types of methods to trigger measurement ormeasurement reporting may be used depending on a current situation. Forexample, in case of proximity discovery when UE is not currently engagedin D2D communication, periodic or continuous proximity discovery may notbe required. A single measurement or attempt at measurement for acertain measurement period may be sufficient to detecting whetheranother device is close enough to the UE. However, in the case ofproximity discovery during D2D communication, periodic or continuousmeasurement may be required to manage D2D communication and ensure thatthe devices are close enough to carry on the D2D communication.

According to one embodiment, both open and restricted proximitydiscovery are possible with a D2D-enabled network and D2D-enabled UEs.In other words, proximity discovery may be possible with or withoutexplicit permission from a UE being discovered. In case of openproximity discovery, the UE may be required to measure reference signalsfrom a large number of UEs if there are many D2D UEs in proximity andmay only detect a small number of UEs which actually allow themselves tobe discovered. In case of restricted proximity discovery, an eNB may beconfigured to provide information regarding UEs that are available fordiscovery to a UE to reduce effort required by the UE for detection.

FIG. 1 is a schematic diagram illustrating a communication system 100for UE-assisted proximity discovery. The communication system 100includes a plurality of UEs 102, at least one evolved Node B (eNB) 104,and a core network 106. According to one embodiment, the eNBs 104 andcore network 106 provide communication services, data services, and/orother operator services to the UEs 102. For example, the core network106 may provide access to voice services, media services, the Internet,and/or other communication, location, or data services.

In one embodiment, the UEs 102, eNBs 104, and core network 106 areD2D-enabled. For example, the UEs 102 may be capable of D2Dcommunication with each other and the eNBs 104 and core network 106 maybe configured to assist in proximity discovery and D2D communicationestablishment between the UEs 102. In one embodiment, one or more of theUEs 102 are configured to attempt to identify other UEs 102 that arewithin proximity. A UE 102 may measure signal quality or signal strengthof a received discovery signal transmitted by another UE 102. The UE 102may then send a measurement report to an eNB 104 which may determinewhether the UEs 102 are in proximity and/or configure a D2Dcommunication between UEs 102.

Some of the UEs 102 are involved in a first D2D communication session108, a second D2D communication session 110, and a D2D groupcommunication session 112. The first D2D communication session 108involves two UEs 102 located within a coverage region 114 for the sameeNB 104. According to one embodiment, because the UEs 102 cancommunicate with the same eNB 104, a single eNB 104 may be able toidentify the proximity of the UEs 102 and/or configure the first D2Dcommunication session 108. For example, the eNB 104 may not need tocommunicate with the core network 106 in order to establish the firstD2D communication session 108. The second D2D communication session 110involves two UEs 102 that are located within coverage regions 114 ofdifferent eNBs 104. According to one embodiment, because the UEs 102cannot communicate with the same eNB 104, the eNBs 104 must communicatewith each other and/or the core network 106 in order to identify theproximity of the UEs 102 and/or configure the second D2D communicationsession 110. In one embodiment, an eNB 104 may communicate with anothereNB 104 to locate UEs 102 that may be connected to the other eNB 104 butnevertheless are in proximity for D2D communication. For example, eacheNB 104 may need to communicate with neighboring eNBs 104 and arespective UE 102 in order to establish the second D2D communicationsession 110.

The D2D group communication session 112 involves more than two UEs 102involved with each other in the D2D group communication session 112. Forexample, each UE 102 in the D2D group communication session 112 isinvolved in D2D communication with two other UEs 102. Three or more UEs102 involved in a group communication session 112 may be referred to asa D2D group.

The plurality of UEs 102 may include any type of mobile communicationdevice or computing device. For example, the UEs 102 may include mobilephones such as smart phones, tablet computers, personal digitalassistants (PDAs), notebook computers, Ultrabook™ computers, or othercommunication or computing devices. The UEs 102 may also include lowmobility or fixed location devices which nevertheless accesscommunication or networking services via the eNBs 104 and/or corenetwork 106. The eNBs 104 may include other types of radios depending onother embodiments and an implemented communication protocol.

FIG. 2 illustrates an example of a UE 102 and an eNB 104 communicatingto configure and report proximity measurements, according to oneembodiment. The UE 102 includes a transceiver component 202 and aprocessing component 208. The processing component 208 is configured togenerate capability information, measure reference signals, and generatemeasurement reports as well as perform other functions of the UE 102 asdescribed herein. The transceiver component 202 includes a receivercomponent 204 configured to receive reference signals, configurationinformation, and other signals and messages as described herein. Thetransceiver component 202 also includes a transmission component 206configured to transmit capability information, measurement reports, andother signals and messages as described herein.

The eNB 104 includes a transceiver component 212 and a processingcomponent 218. The processing component 218 is configured to generateconfiguration information for the UE 102, determine a capability of theUE 102, determine a proximity of a device to the UE 102 based onmeasurement reports, and perform other functions of the eNB 104 asdescribed herein. The transceiver component 212 includes a receivercomponent 214 configured to receive measurement reports, capabilityinformation, and other signals and messages as described herein. Thetransceiver component 212 also includes a transmission component 216configured to transmit configuration information, transmit messages toconfigure a D2D session, and to transmit other signals and messages asdescribed herein.

FIG. 3 is a diagram of a communication message flow illustrating acommunication procedure 300 between a UE 102 and an eNB 104 toconfigure, measure, and report proximity detection measurements,according to one embodiment. The communication procedure 300 may beperformed to determine a proximity of another UE 102 or device. Thecommunication procedure 300 may be performed, for example, in responseto the UE 102 executing an application that can utilize proximity-basedservices. The application and/or the UE 102 may determine thatproximity-based services may be required or be helpful to the operationof the UE 102. Similarly, the communication procedure 300 may beperformed in response to the eNB 104 detecting traffic that may berouted over a D2D path to reduce a load on network infrastructure and/orto provide proximity-based services to one or more UEs 102.

The eNB 104 enquires 302 as to the capabilities of the UE 102. The eNB104 may enquire 302 as to the capabilities of the UE 102 by sending aproximity detection (PD) measurement capability enquiry message. Theenquiry 302 may request specific information regarding the UE'scapabilities including whether the UE 102 is capable of D2Dcommunication, the types of D2D communication for which the UE 102 isconfigured, and/or whether the UE 102 is capable of simultaneoustransmission or reception of additional signals while receiving PD-RS.The latter capability may be used by the UE 102 to indicate whether itsupports the following cases to the eNB 104. In the first case the UE102 can measure incoming PD-RS while it simultaneously transmits PD-RSfor another UEs' proximity discovery. In the second case the UE 102 canmeasure incoming PD-RS while it simultaneously transmits LTE uplinksignal to the eNB 104 or transmits signals to other D2D-enabled UEs 102.In the third case the UE 102 can measure incoming PD-RS while itsimultaneously receives LTE downlink signal from the eNB 104 or receivessignals from other D2D-enabled UEs 102.

The UE 102 provides 304 capability information to the eNB 104 indicatingcapabilities of the UE 102. For example, the UE 102 may provide 304 a PDmeasurement capability information message that indicates thecapabilities of the UE 102. The capability information may indicatewhether the UE 102 is capable of simultaneous transmission or receptionof additional signals while receiving PD-RS. For example, if the UE 102includes only a single radio frequency (RF) chain, the UE 102 may not becapable of measuring an incoming signal while simultaneouslytransmitting a signal. Additionally, the capability information provided304 by the UE 102 may indicate D2D protocols and interfaces throughwhich the UE 102 is capable of direct communication. For example, thecapability information may indicate that the UE 102 is capable of directcommunication using LTE direct, WiFi direct, Bluetooth, and/or otherprotocols or standards.

The eNB 104 provides 306 measurement configuration information to the UE102. The eNB 104 may provide 306 a PD measurement configuration messagethat includes a variety of settings and values to configure the UE 102for PD-RS measurement. In one embodiment, the eNB 104 may provide amessage indicating one or more of a measurement gap pattern, radioresource configuration information for a proximity discovery referencesignal (PD-RS), an event definition, a reporting interval, a discoverytype (e.g., open or restricted), and/or a plurality of other types ofsettings.

In one embodiment, the eNB 104 provides 306 measurement configurationinformation that includes a measurement gap pattern. For example, if thecapability information provided 304 by the UE 102 indicates that the UEis not capable of simultaneous transmission or reception of additionalsignals while receiving PD-RS, the eNB 104 may provide 306 a measurementgap pattern that configures the UE 102 to measure incoming PD-RS signalsduring a measurement gap and prohibits the UE 102 from transmitting orreceiving signals during the measurement gap.

Measurement gaps may be needed because, at least in some embodiments,proximity discovery and D2D communication are supported using a ULresource. For example, PD-RS may be transmitted on uplink resource suchas in LTE frequency division duplex (FDD) mode or LTE time divisionduplex (TDD) mode. In LTE FDD mode, PD-RS may be transmitted in theuplink subframes of the uplink frequency band while in LTE TDD mode thePD-RS may be transmitted in the subframes reserved for uplinktransmission of the TDD frequency band. Therefore, if a UE 102 has onlyone RF chain, the UE 102 may be required to transmit and receive signalssimultaneously, unless measurement gaps are configured. In the casewhere a UE 102 is able to transmit and receive signals simultaneously, ameasurement gap pattern and/or measurement gap may not need to beconfigured.

FIG. 4 illustrates a measurement gap table 400 illustrating examplemeasurement gap patterns which may be configured in the UE 102 by theeNB 104. The gap patterns identified as “0” and “1” in the “Gap PatternID” column represent LTE gap pattern configurations defined in LTE thatmay be reused for measurement gap patterns for proximity detection. Forexample, the “Measurement Purpose” column indicates the purposes forwhich the gap patterns “0” and “1” were implemented, and the LTEstandard may be modified to include a further purpose for proximitydetection and/or D2D communication. In one embodiment, a singlemeasurement gap pattern may be shared for both proximity detectionmeasurements as well as for other measurement purposes. For example, ifthe UE 102 needs to perform both PD-RS measurement and othermeasurements requiring a measurement gap, e.g., inter-frequency orinter-radio access technology (RAT) measurements, the measurement gapcan be shared for both PD-RS measurement and other measurements. In casethe length of the measurement gap is not sufficient to perform bothPD-RS measurement and inter-frequency or inter-RAT measurement, thenPD-RS measurement may be prioritized such that inter-frequency and/orinter-RAT measurement is performed after PD-RS measurement is completed.Alternatively, inter-frequency and/or inter-RAT measurements may beprioritized and thus, PD-RS measurement may be performed after theinter-frequency and/or inter-RAT measurement is completed. Theprioritization of the measurements may be included within themeasurement gap pattern configuration or may be left for implementationin the UE 102.

In one embodiment, a measurement gap pattern configuration optimized forPD-RS measurement may also be configurable. For example, in order tosave the UE 102 power consumption as much as possible, a differentperiodicity for a proximity detection measurement gap may be desirable.In one embodiment, the periodicity of a measurement gap to measurePD-RSs is longer than that of a cell reference signal (CRS). The gappattern “2” in FIG. 4 illustrates one embodiment of a proximitydetection-specific measurement gap pattern. The measurement gaprepetition period (MGRP) is listed as N_p which is the minimumperiodicity for any PD-RS to be measured. By matching the period for ameasurement gap pattern to the PD-RS, reduced energy usage may beaccomplished for the UE 102. Similar to gap patterns “0” and “1,” themeasurement gap of gap pattern “2” may be shared for other measurementpurposes.

Returning to FIG. 3, the eNB 104 may provide 306 measurementconfiguration information that includes radio resource configurationinformation for a proximity discovery reference signal. For example, theeNB 104 may provide 306 radio resource configuration information for adevice that is discoverable by the UE 102. The radio resourceconfiguration information may include information to allow the UE 102 tomore easily locate a signal that is discoverable and also allow the UE102 to more quickly and/or accurately determine a signal parameter of aPD-RS that corresponds to the other device. The radio resourceconfiguration information may include a transmission offset thatindicates a transmission power for a corresponding PD-RS. ThisPD-RS-specific transmission offset may only be required when theproximity discovery signal is transmitted with a different transmitpower. For example, if all UEs 102 transmit proximity discovery signalswith a same power (e.g., a maximum transmit power), PD-RS-specifictransmission offsets may not be required. Thus, the measurement of thePD-RS may be used to more accurately and quickly determine a signalparameter of the other device and/or a proximity of the other device. Inone embodiment, the radio resource configuration information includes anidentifier for the PD-RS and/or a device that is transmitting the PD-RS.

In one embodiment, the UE 102 may store a PD-RS list of signals whichare to be measured by the UE 102. The PD-RS list may store anidentifier, transmission offset, or other information specific to aPD-RS to be measured by the UE. The PD-RS list may include radioresource configuration information or other information received fromthe eNB 104. For example, each time the UE 102 receives radio resourceconfiguration information from the eNB 104, the UE 102 may update thePD-RS list to reflect the new radio resource configuration information.According to one embodiment, the eNB 104 maintains the PD-RS list bycontrolling what is included in the PD-RS list. In one embodiment, theeNB 104 may transmit a message to add, modify, or remove a PD-RS of thePD-RS list. For example, a PD-RS addition or replacement message to addor modify a PD-RS may include an identifier and radio resourceconfiguration information for the PD-RS. In one embodiment, the eNB canadd a new PD-RS to the PD-RS list or modify an existing PD-RS bysignaling a PD measurement configuration message with aPD-RSToAddModList information. A PD-RS removal message to remove a PD-RSfrom the PD-RS list may include an index corresponding to the PD-RS tobe removed. In one embodiment, only an index is needed because eachPD-RS in the PD-RS list includes its own unique index in the list. Anexisting PD-RS entry can be removed from the PD-RS list by signaling aPD measurement configuration message with a PD-RSToRemoveListinformation.

According to one embodiment, the eNB 104 may provide 306 measurementconfiguration information that includes an event definition and/or areporting interval defining when to report measurement data to the eNB104. An event definition may define an occurrence that triggersreporting of a measurement for a PD-RS or for multiple PD-RSs. Areporting interval may define a time interval on which measurementreports for any measured PD-RSs or a subset of measured PD-RSs should bereported. In one embodiment, a reporting interval may configure the UE102 to provide a measurement report periodically on the reportinginterval regardless of whether the event is detected. In anotherembodiment, a reporting interval may configure the UE 102 to provide ameasurement report periodically on the reporting interval in response todetecting the event. Further discussion of measurement reporting andtriggering of measurement reporting will be discussed below in relationto providing 310 a PD measurement report of FIG. 3 and FIGS. 5, 6, 7,and 8.

According to one embodiment, the eNB 104 provides 306 measurementconfiguration information that indicates a discovery type to beperformed by the UE 102. In one embodiment, the eNB 104 selectivelyconfigures the UE 102 to perform an open proximity discovery wherein theUE 102 is free to perform proximity discovery measurements on any PD-RSit detects. For example, even if the UE 102 stores a PD-RS list and/orif the eNB 104 provides radio resource configuration information for oneor more PD-RSs, the UE 102 may be configured to perform proximitydiscovery on a PD-RS that does not correspond to an entry in the PD-RSlist or radio resource configuration information provided by the eNB104. Alternatively, the eNB 104 may selectively configure the UE 102 toperform restricted proximity discovery. In restricted proximitydiscovery, the UE 102 may only perform measurements on PD-RSs for whichthe UE 102 has received radio resource configuration information orother information from the eNB 104. For example, the UE 102 may onlyperform measurements on PD-RSs in a PD-RS list stored on the UE 102 whenthe UE 102 is configured for restricted proximity discovery.

The following shows an example of ASN.1 coding for MeasObjectEUTRA toconfigure a measurement object, such as a PD-RS, with the UE 102:

MeasObjectEUTRA ::= SEQUENCE { carrierFreq ARFCN-ValueEUTRA,allowedMeasBandwidth AllowedMeasBandwidth, presenceAntennaPort1PresenceAntennaPort1, neighCellConfig NeighCellConfig, offsetFreqQ-OffsetRange DEFAULT dB0, -- Cell list cellsToRemoveList CellIndexListOPTIONAL, -- Need ON cellsToAddModList CellsToAddModList OPTIONAL, --Need ON -- Black list blackCellsToRemoveList CellIndexList OPTIONAL, --Need ON blackCellsToAddModList BlackCellsToAddModList OPTIONAL, -- NeedON cellForWhichToReportCGI PhysCellId OPTIONAL, -- Need ON ...,[[measCycleSCell-r10 MeasCycleSCell-r10 OPTIONAL, -- Need ONmeasSubframePatternConfigNeigh-r10 MeasSubframePatternConfigNeigh-r10OPTIONAL -- Need ON ]], typePD-RSMeas ENUMERATED{open, restricted}OPTIONAL, -- Need ON pD-RSToRemoveList PD-RSIndexList OPTIONAL, -- Condirestricted pD-RSToAddModList PD-RSToAddModList OPTIONAL -- Condirestricted } PD-RSToAddModList ::= SEQUENCE (SIZE (1..maxPD-RSMeas)) OFPD-RSToAddMod PD-RSToAddMod ::= SEQUENCE { pD-RSIndex INTEGER (1..maxPD-RSMeas), pD-RSresourceConf PD-RSresourceConf,pD-RSIndividualOffset OffsetRange } PD-RSIndexList :: = SEQUENCE(SIZE(1...maxPD-RSMeas)) OF PD-RSIndex PD-RSIndex ::=INTEGER(1..maxPD-RSMeas) PD-RSresourceConf ::= SEQUENCE {pD-RSresourceConfig INTEGER (0..99), pD-RSsubframeConfig INTEGER (0..9)} maxPD-RSMeas INTEGER ::= 64 -- Maximum number of PD-RS to measuremaxPD-RS INTEGER ::= 128 -- Maximum number of PD-RS OffsetRange ::=ENUMERATED { dB-24, dB-22, dB-20, dB-18, dB-16, dB-14, dB-12, dB-10,dB-8, dB-6, dB-5, dB-4, dB-3, dB-2, dB-1, dB0, dB1, dB2, dB3, dB4, dB5,dB6, dB8, dB10, dB12, dB14, dB16, dB18, dB20, dB22, dB24}

The field typePD-RSMeas indicates whether PD-RS measurement is in anopen discovery mode or restricted discovery mode. If it is in an opendiscovery mode, the UE 102 can measure a PD-RS which is not in the PD-RSlist. Otherwise, the UE 102 measures PD-RS configured in the PD-RS listonly (restricted mode). The field pD-RSToRemoveList may be used toindicate a list of PD-RSs to remove from the PD-RS list. The fieldpD-RSToAddModList may be used to indicate a list of PD-RSs to add ormodify in the PD-RS list. The field pD-RSIndex indicates an index of aPD-RS in the PD-RS list. The field pD-RSresourceConf indicates the radioresource configuration for a PD-RS. The field pD-RSIndividualOffsetindicates a PD-RS specific transmission offset for a specific PD-RS. Thevalues dB-24, dB-22, etc in the OffsetRange correspond to −24 dB, −22dB, and so on. In one embodiment, the fields pD-RSToRemoveList andpD-RSToAddModList are mandatory in the case where typePD-RSMeas is setto restricted and are not needed when typePD-RSMeas is set to open.

In one embodiment, a new measurement object MeasObjectD2D can beintroduced instead of modifying the MeasObjectEUTRA object asillustrated above:

MeasObjectD2D ::= SEQUENCE { carrierFreq ARFCN-ValueEUTRA, typePD-RSMeasENUMERATED{open, restricted} OPTIONAL, -- Need ON pD-RSToRemoveListPD-RSIndexList OPTIONAL, -- Condi restricted pD-RSToAddModListPD-RSToAddModList OPTIONAL -- Condi restricted } PD-RSToAddModList ::=SEQUENCE (SIZE (1..maxPD-RSMeas)) OF PD-RSToAddMod PD-RSToAddMod ::=SEQUENCE { pD-RSIndex INTEGER (1.. maxPD-RSMeas), pD-RSresourceConfPD-RSresourceConf, pD-RSIndividualOffset OffsetRange } PD-RSIndexList ::= SEQUENCE (SIZE(1...maxPD-RSMeas)) OF PD-RSIndex PD-RSIndex ::=INTEGER(1..maxPD-RSMeas) PD-RSresourceConf ::= SEQUENCE {pD-RSresourceConfig INTEGER (0..99), pD-RSsubframeConfig INTEGER (0..9)} maxPD-RSMeas INTEGER ::= 64 -- Maximum number of PD-RS to measuremaxPD-RS INTEGER ::= 128 -- Maximum number of PD-RS OffsetRange ::=ENUMERATED { dB-24, dB-22, dB-20, dB-18, dB-16, dB-14, dB-12, dB-10,dB-8, dB-6, dB-5, dB-4, dB-3, dB-2, dB-1, dB0, dB1, dB2, dB3, dB4, dB5,dB6, dB8, dB10, dB12, dB14, dB16, dB18, dB20, dB22, dB24}

Returning to FIG. 3, the UE 102 measures 308 PD-RS signals based on thereceived configuration information. For example, the UE 102 may measureone or more PD-RS signals located in a PD-RS list to determine a signalparameter for each PD-RS. The signal parameter may include a signalstrength, signal to noise ratio, signal to interference ratio (SIR), orother signal parameter of the PD-RS that may be helpful for proximitydetection. In one embodiment, the UE 102 measures 308 the PD-RS signalsduring a measurement gap and prohibits UL transmission during themeasurement gap, as configured by the eNB 104. The UE 102 may also beconfigured to determine whether a specific PD-RS corresponds to a devicethat is engaged in D2D communication with the UE 102. In one embodiment,a PD-RS that corresponds to a device engaged in D2D communication withthe UE 102 may be measured 308 more frequently than another PD-RS.

The UE 102 reports 310 PD-RS measurements to the eNB 104. The reported310 measurements may include one or more signal parameters determined bythe UE 102. In one embodiment, the eNB 104 wants to receive theinformation regarding whether there are other devices in proximity of aUE 102. The UE 102 measures each PD-RS that is detected during ameasurement period, such as a measurement gap. A single attempt atsignal detection and measurement may be sufficient as long as themeasurement is reliable and as long as the UE measures sufficientpercentage of detected PD-RSs. The UE 102 may or may not need to performperiodic PD-RS measurements for proximity discovery to see if there areany nearby devices. Although there may be minimal requirements forfrequency of PD-RS measurement prior to establishing a D2D session, thiscan change significantly following establishing of a D2D communicationsession. For example, after the D2D session is established, it is alsogenerally necessary to determine whether the devices continue to remainin proximity and/or whether any additional devices come into proximityof the UE 102. Therefore, more frequent measurement reporting to managea D2D session may be required.

Three types of measurement reporting methods may need to be consideredfor supporting different implementations of proximity discovery and D2Dcommunication including event-triggered reporting, periodic reporting,and periodic reporting after event triggering.

In event-triggered reporting a UE 102 can send a measurement report whena measurement meets one or more reporting criteria as defined in anevent definition. In one embodiment, the UE 102 sends a PD measurementreport to the eNB 104 in response to a triggering event. For example, anevent definition received from the eNB 104 may define an occurrence of atriggering event. The UE 102 may detect occurrence of the event andreport 310 a measurement to the eNB 104. The occurrence of the eventand/or the measurement report may be used by the eNB 104 to determinewhether a UE 102 is close enough to another UE 102 in order to beinvolved in a D2D communication session. In one embodiment, the eventincludes a change of a signal parameter of a PD-RS that indicatesanother device has moved within or out of range of the UE 102.Event-triggered reporting may be beneficial to save the amount ofreporting signaling because the UE 102 can send the measurement reportsonly when the signal quality of a PD-RS has changed (e.g., has becomestrong enough to connect or weak enough to drop D2D communication).

In one embodiment, an event definition defines an occurrence of a signalparameter for a PD-RS exceeding an absolute threshold. Detection of aPD-RS exceeding an absolute threshold may be useful to determine whethera corresponding device can participate in a D2D session with the UE 102,regardless of whether or not the UE 102 is already involved in a D2Dsession. A UE 102 may compare measurements for a PD-RS to one or moreconditions defining the occurrence of the PD-RS exceeding an absolutethreshold. In one embodiment, an entering condition for exceeding anabsolute threshold is determined based on equation (1) below and aleaving condition for falling below an absolute threshold is determinedbased on equation (2) below.

Ms−Hys>Thresh  (1)

Ms+Hys<Thresh  (2)

Ms corresponds to measured value for the PD-RS, Hys corresponds to ahysteresis value defined by the eNB 104 or in the UE 102, and Threshcorresponds to the absolute threshold value. Ms may be a measurement ofreceived signal strength in dBm, a measurement of a signal tointerference ratio (SIR) in dB, or any other signal parameter. Theparameters Hys and Thresh may be configured through RRC (Radio ResourceControl protocol sublayer) signaling between the UE 102 and eNB 104.According to one embodiment, a measurement report is triggered inresponse to the occurrence of the entering condition.

FIG. 5 is a signal parameter graph 500 illustrating a signal parametervalue Ms of a PD-RS over time as measured by the UE 102. The graph 500includes a line 502 that illustrates a measured value for a signalparameter over time. The dots on line 502 indicate points at which theUE 102 measures the PD-RS to obtain the value Ms. The graph 500 alsoshows an absolute threshold value 504 as well as hysteresis values 506and 508 above and below the absolute threshold value 504. Point 510indicates when the UE 102 detects the occurrence of the enteringcondition and point 512 indicates where the UE 102 detects theoccurrence of the leaving condition. In one embodiment, in response todetecting the entering condition the UE 102 may trigger a measurementreport of a current value of the signal parameter to the eNB 104.

In one embodiment, an event definition defines an occurrence of a signalparameter for a PD-RS falling below an absolute threshold. Detection ofa PD-RS falling below an absolute threshold may be useful fordetermining whether a D2D session should be terminated and/or ifcommunication flows should be switched to an infrastructurecommunication path. In one embodiment, an entering condition for fallingbelow the absolute threshold is determined based on equation (3) belowand a leaving condition for exceeding the absolute threshold isdetermined based on equation (4) below.

Ms+Hys<Thresh  (3)

Ms−Hys>Thresh  (4)

According to one embodiment, a measurement report is triggered inresponse to the occurrence of the entering condition. In one embodiment,the UE 102 may also determine whether the PD-RS corresponds to a devicewith which the UE 102 is in D2D communication before sending themeasurement report.

FIG. 6 is a signal parameter graph 600 illustrating a signal parametervalue Ms of a PD-RS over time as measured by the UE 102. The graph 600includes a line 602 that illustrates a measured value for a signalparameter over time. The graph 600 also shows the absolute thresholdvalue 504 as well as hysteresis values 506 and 508 of FIG. 5. Point 610indicates when the UE 102 detects the occurrence of the enteringcondition and point 612 indicates where the UE 102 detects theoccurrence of the leaving condition. In one embodiment, in response todetecting the entering condition the UE 102 may trigger a measurementreport of a current value of the signal parameter to the eNB 104.

In one embodiment, the event definition defines occurrence of a signalparameter for a PD-RS and one or more additional PD-RSs exceeding anabsolute threshold. For example, the event may define the occurrence ofmultiple PD-RSs exceeding an absolute threshold as defined by equations(1) and (2) above. Determining whether multiple UEs 102 have PD-RSs thatexceed an absolute threshold may be useful in establishing a group D2Dcommunication session. FIG. 7 illustrates an example of multiple signals702, 704, and 706 exceeding the threshold based on equations (1) and (2)above. A UE 102 may detect occurrence of the signals 702, 704, and 706all exceeding the threshold at point 708.

In one embodiment, an event definition defines an occurrence of a signalparameter for a PD-RS improving above a corresponding signal parameterfor another PD-RS. For example, the event may define the occurrence of afirst signal parameter improving above the second signal parameter.Determining comparative signal quality and/or proximity may be useful indetermining which device can have the best connection with a given UE102. The eNB 104 may be able to use this information to create a moreefficient communication path between D2D-enabled UEs 102. The secondsignal parameter may correspond to a best PD-RS and/or a PD-RS of adevice that is engaged in D2D communication with the UE 102. In oneembodiment, an entering condition for improving above a correspondingsignal parameter is determined based on equation (5) below and a leavingcondition for falling below a corresponding signal parameter isdetermined based on equation (6) below.

Ms+Ocn−Hys>MRef+Ocb+Off  (5)

Ms+Ocn+Hys<MRef+Ocb+Off  (6)

MRef may correspond to a reference signal against which a PD-RS is beingcompared. For example, MRef may be the PD-RS for a device engaged in D2Dcommunication with the UE 102, the best or strongest PD-RS in terms ofsignal quality detected by the UE 102. In one embodiment, which PD-RS touse as MRef may be configured by the eNB 104 and/or may correspond to anitem in a PD-RS list with a lowest index. Ocn is the PD-RS specificoffset for the measured value Ms. Ocb is the PD-RS specific offset forthe reference signal MRef. For example, Ocn and Ocb may be thetransmission offset provided as part of radio resource configurationinformation by the eNB 104 during configuration of the UE 102. Ocn andOcb may be omitted, or may be zero, if all PD-RS are transmitted withthe same power. Off may be an offset parameter (similar to Hys ofequations 1-4). According to one embodiment, a measurement report istriggered in response to the entering condition. In one embodiment, theUE 102 may also determine whether the PD-RS corresponds to a device withwhich the UE 102 is in D2D communication before sending the measurementreport.

FIG. 8 is a signal parameter graph 800 illustrating a signal parametervalue Ms plus a transmission offset Ocn (Ms+Ocn) of a PD-RS over time asmeasured by the UE 102. The graph 800 includes a line 802 thatillustrates a measured value for the signal parameter plus thetransmission offset (Ms+Ocn) over time. The graph 800 also shows thereference threshold value 804 (MRef+Ocb+Off) as well as offset values806 (MRef+Ocb+Off+Hys) and 808 (MRef+Ocb+Off−Hys). Point 812 indicateswhen the UE 102 detects the occurrence of the entering condition andpoint 810 indicates where the UE 102 detects the occurrence of theleaving condition. In one embodiment, in response to detecting theentering condition the UE 102 may trigger a measurement report of acurrent value of the signal parameter to the eNB 104. As illustrated inFIG. 8, Mref+Ocb+Off may vary with time because it is based on areference PD-RS (MRef).

In periodic reporting a UE 102 may report measurement results of anymeasured PD-RS every reporting interval. A reporting interval forproximity discovery signal can be configured by the eNB 104 orpredefined in the specification. For proximity discovery purposes only,the UE 102 may not need to measure PD-RS periodically and measurementand/or reports may only be provided when requested by the eNB 104. Areporting amount value (e.g., reportAmount) can be provided by the eNB104 to configure the UE 102 to send either a single measurement report(e.g., reportAmount=1) or multiple reports (e.g., reportAmount isgreater than one, or even unlimited). In one embodiment, if a UE 102 isconfigured to send only one report, it may be desirable to give enoughtime for the UE 102 to detect other UEs 102 in proximity. Therefore, themonitoring time may be defined before the UE 102 sends a firstmeasurement report and/or if at least a minimum number (e.g., N) ofPD-RSs are available in the UE, where the minimum number is eitherpredefined (e.g., N=1) or configured by the eNB 104 through RRCsignaling.

In periodic reporting after event triggering, the UE 102 can sendperiodic reporting in response to a measurement meeting one of the aboveevent triggered conditions.

The following is the example of ASN.1 coding for measurement reporting:

ReportConfigPD-RS ::= SEQUENCE { triggerType CHOICE { event SEQUENCE {eventId CHOICE { eventD1 SEQUENCE { d1-Threshold ThresholdEUTRA },eventD2 SEQUENCE { d2-Threshold ThresholdEUTRA }, eventD3 SEQUENCE {d3-OffsetRef INTEGER (−30..30), d3-OffbestBest INTEGER (−30..30),d3-Offset INTEGER (−30..30) }, eventD4 SEQUENCE { d4-numberPD-RS INTEGER(1..maxPD-RS), d4-Threshold ThresholdEUTRA }, ... } }, hysteresisHysteresis, timeToTrigger TimeToTrigger }, Periodical SEQUENCE { purposeENUMERATED { reportStrongestPD-RS, ...} } }, triggerQuantity ENUMERATED{rsrp, rsrq}, reportQuantity ENUMERATED {sameAsTriggerQuantity, both},reportInterval ReportInterval, reportAmount ENUMERATED {r1 , r2, r4, r8,r16, r32, r64, infinity}, ... } ThresholdEUTRA ::= CHOICE{threshold-RSRP RSRP-Range, threshold-RSRQ RSRQ-Range } Hysteresis ::=INTEGER (0..30) ReportInterval ::= ENUMERATED {ms120, ms240, ms480,ms640, ms1024, ms2048, ms5120, ms10240,min1, min6, min12, min30, min60,spare3, spare2, spare1} RSRP-Range ::= INTEGER(0..97) RSRQ-Range ::=INTEGER(0..34) TimeToTrigger ::= ENUMERATED { ms0, ms40, ms64, ms80,ms100, ms128, ms160, ms256, ms320, ms480, ms512, ms640, ms1024, ms1280,ms2560, ms5120} maxPD-RS INTEGER ::= 128  -- Maximum number of PD-RS

The field eventID indicates a choice of PD-RS event triggered reportingcriteria. The field Hysteresis is a parameter used within the entry andleave condition of an event-triggered reporting condition, such as theHys variable included in equations (1) through (4). The actual value ofHysteresis in one embodiment is (Information Element (IE) value)*0.5 dB,where the IE value refers to a value fo Hysteresis as signaled as partof the measurement reporting configuration via ReportConfigPD-RS. Thefield reportAmount indicates a number of measurement reports applicablefor the triggerType event as well as for the triggerType periodical. Thefield ReportInterval indicates a time interval between periodicalreports.

The ReportInterval is applicable if the UE 102 performs periodicalreporting (i.e., when reportAmount exceeds 1). The value ms120corresponds with 120 ms, ms240 corresponds with 240 ms and so on, whilevalue mini corresponds with 1 minute, min6 corresponds with 6 minutesand so on. The field reportQuantity indicates quantities to be includedin a measurement report. The value both means that both the referencesignal received power (RSRP) and the reference signal receive quality(RSRQ) quantities are to be included in the measurement report. Thefield ThresholdEUTRA indicates a threshold for event evaluation. ForRSRP the actual threshold value is (IE value—140) dBm. For RSRQ theactual threshold value is (IE value—40)/2 dB. The field timeToTriggerindicates the time in ms during which specific criteria for the eventneeds to be met in order to trigger a measurement report. The fieldtriggerQuantity indicates the quantities used to evaluate the triggeringcondition for the event. The values RSRP and RSRQ correspond toproximity discovery reference signal received power (PD-RSRP) andreference signal received quality (PD-RSRQ).

FIG. 9 is a diagram of a communication message flow illustrating acommunication procedure 900 between a UE 102 and an eNB 104 toconfigure, measure, and report proximity detection measurements,according to one embodiment.

The UE 102 and eNB 104 configure 902 proximity measurement. In oneembodiment, the proximity measurement may be configured 902 in a mannersimilar to that discussed in relation to FIG. 3. For example,configuring 902 proximity measurement may include the eNB 104 enquiring302 as to the capabilities of the UE 102, the UE 102 providing 304capability information, and the eNB 104 providing 306 measurementconfiguration information to the UE 102, with any of the variation asdiscussed herein.

The proximity UEs 102 may transmit PD-RS 904 which are then measured 906by the UE 102. The UE 102 then provides 310 measurement reports to theeNB 104. The measurement reports may be provided 310 based on eventtriggered reporting, periodic reporting, and periodic reporting afterevent triggering as discussed above.

Based on the received measurement reports, the eNB 104 configures 908the UE 102 and any proximity UEs 102 for D2D communication. For example,the eNB 104 may configure 908 D2D communication when the measurementreports provided 310 by the UE 102 indicate that the proximity UEs 102are close enough to establish D2D communication. Based on theconfiguration 908 from the eNB 104, the UE 102 and any proximity UEs 102start 910 D2D communication.

The UE 102 continues to measure PD-RSs 906 from the proximity UEs 102 tomonitor D2D communication and/or to detect additional UEs 102 that comewithin proximity. The UE 102 also continues to provide 310 measurementreports as configured 902 by the eNB 104. According to one embodiment,the eNB 104 may modify the D2D communication and/or end D2Dcommunication based on the measurement reports provided 310 by the UE102.

FIG. 10 provides an example illustration of a mobile device, such as auser equipment (UE), a mobile station (MS), a mobile wireless device, amobile communication device, a tablet, a handset, or another type ofmobile wireless device. The mobile device can include one or moreantennas configured to communicate with a transmission station, such asa base station (BS), an evolved Node B (eNB), a base band unit (BBU), aremote radio head (RRH), a remote radio equipment (RRE), a relay station(RS), a radio equipment (RE), or another type of wireless wide areanetwork (WWAN) access point. The mobile device can be configured tocommunicate using at least one wireless communication standard including3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and/orWiFi. The mobile device can communicate using separate antennas for eachwireless communication standard or shared antennas for multiple wirelesscommunication standards. The mobile device can communicate in a wirelesslocal area network (WLAN), a wireless personal area network (WPAN),and/or a WWAN.

FIG. 10 also provides an illustration of a microphone and one or morespeakers that can be used for audio input and output from the mobiledevice. The display screen may be a liquid crystal display (LCD) screenor other type of display screen, such as an organic light emitting diode(OLED) display. The display screen can be configured as a touch screen.The touch screen may use capacitive, resistive, or another type of touchscreen technology. An application processor and a graphics processor canbe coupled to internal memory to provide processing and displaycapabilities. A non-volatile memory port can also be used to providedata input/output options to a user. The non-volatile memory port mayalso be used to expand the memory capabilities of the mobile device. Akeyboard may be integrated with the mobile device or wirelesslyconnected to the mobile device to provide additional user input. Avirtual keyboard may also be provided using the touch screen.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, a non-transitorycomputer readable storage medium, or any other machine-readable storagemedium wherein, when the program code is loaded into and executed by amachine, such as a computer, the machine becomes an apparatus forpracticing the various techniques. In the case of program code executionon programmable computers, the computing device may include a processor,a storage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device. The volatile and non-volatile memoryand/or storage elements may be a RAM, EPROM, flash drive, optical drive,magnetic hard drive, or other medium for storing electronic data. TheeNB (or other base station) and UE (or other mobile station) may alsoinclude a transceiver component, a counter component, a processingcomponent, and/or a clock component or timer component. One or moreprograms that may implement or utilize the various techniques describedherein may use an application programming interface (API), reusablecontrols, and the like. Such programs may be implemented in a high levelprocedural or object oriented programming language to communicate with acomputer system. However, the program(s) may be implemented in assemblyor machine language, if desired. In any case, the language may be acompiled or interpreted language, and combined with hardwareimplementations.

It should be understood that many of the functional units described inthis specification may be implemented as one or more components, whichis a term used to more particularly emphasize their implementationindependence. For example, a component may be implemented as a hardwarecircuit comprising custom VLSI circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A component may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, or the like.

Components may also be implemented in software for execution by varioustypes of processors. An identified component of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedcomponent need not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the component and achieve the statedpurpose for the component.

Indeed, a component of executable code may be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within components, and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set, or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork. The components may be passive or active, including agentsoperable to perform desired functions.

Reference throughout this specification to “an example” means that aparticular feature, structure, or characteristic described in connectionwith the example is included in at least one embodiment of the presentdisclosure. Thus, appearances of the phrase “in an example” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and examples of the presentdisclosure may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present disclosure.

Although the foregoing has been described in some detail for purposes ofclarity, it will be apparent that certain changes and modifications maybe made without departing from the principles thereof. It should benoted that there are many alternative ways of implementing both theprocesses and apparatuses described herein. Accordingly, the presentembodiments are to be considered illustrative and not restrictive, andthe disclosure is not to be limited to the details given herein, but maybe modified within the scope and equivalents of the appended claims.

EXAMPLES

The following examples pertain to further embodiments.

Example 1 is a UE that includes processing circuitry. The processingcircuitry is configured to receive and store a PD-RS list from an eNB.The PD-RS list includes a radio resource configuration for at least afirst PD-RS. The processing circuitry measures at least the first PD-RSto determine a signal parameter for the first PD-RS and reports thesignal parameter for the first PD-RS to the eNB.

In Example 2, the radio resource configuration for the first PD-RS ofExample 1 can optionally include a transmission offset. The transmissionoffset indicates a transmission power of the first PD-RS.

In Example 3, the radio resource configuration for the first PD-RS ofExamples 1-2 can optionally include an identifier for the first PD-RS.

In Example 4, the processing circuitry of Examples 1-3 can optionally befurther configured to receive an open discovery mode configuration. Theopen discovery mode configuration configures the UE to measure any PD-RSin addition to the PD-RSs listed in the PD-RS list.

In Example 5, wherein the processing circuitry of Examples 1-4 canoptionally be further configured to receive a restricted discovery modeconfiguration. The restricted discovery mode configuration configuresthe UE to only measure PD-RSs listed in the PD-RS list.

In Example 6, the receiving and storing the PD-RS list of Examples 1-5can optionally include receiving a PD-RS addition message comprising theradio resource configuration for the first PD-RS and storing the radioresource configuration in the PD-RS list.

In Example 7, the receiving and storing the PD-RS list of Examples 1-6can optionally include receiving a PD-RS replacement message comprisingthe radio resource configuration for the first PD-RS and storing theradio resource configuration in the PD-RS list to replace previous radioresource configuration information.

In Example 8, the processing circuitry of Examples 1-7 can optionally befurther configured to receive a PD-RS removal message indicating removalof an entry for a second PD-RS and remove the entry for the second PD-RSfrom the PD-RS list in response to receiving the PD-RS removal message.

In Example 9, a PD-RS removal message of Examples 1-8 can optionallyinclude an index for the entry for the second PD-RS.

Example 10 is a UE including a receiver, a processor, and a transmissioncomponent. The receiver component is configured to receive, from an eNB,measurement report configuration data comprising an event definition.The receiver component is configured to measure a reference signal todetermine a signal parameter for the reference signal. The signalparameter for the reference signal includes a signal strength of thereference signal. The processor is configured to detect an event basedon the signal parameter for the reference signal and the eventdefinition. The event indicates a change in the signal parameter for thereference signal. The transmission component is configured to report, inresponse to detecting the event, the signal parameter for the referencesignal to the eNB.

In Example 11, the event definition of Example 10 defines occurrence ofthe signal parameter for the reference signal exceeding an absolutethreshold.

In Example 12, the event definition of Example 10-11 can optionallydefine occurrence of the signal parameter for the reference signalfalling below an absolute threshold when a device corresponding to thereference signal is in D2D communication with the UE.

In Example 13, the event definition of Examples 10-12 can optionallydefine occurrence of a first signal parameter for the reference signalimproving above a second signal parameter for a reference signal of adevice that is a member of a D2D group comprising the UE.

In Example 14, the event definition of Examples 10-13 can optionallydefine occurrence of the signal parameter for the reference signal andone or more additional reference signal exceeding an absolute threshold.

In Example 15, the processor of Examples 10-14 can optionally beconfigured to determine that the reference signal corresponds to adevice that is engaged in D2D communication with the UE.

In Example 16, the measurement report configuration data received by thereceiver component of Examples 10-15 can optionally further include areporting interval. The measurement report configuration data configuresthe transmission component to provide a measurement report to the eNBone or more of: periodically on the reporting interval regardless ofwhether the event is detected; and periodically on the reportinginterval in response to detecting the event.

Example 17 is a UE that includes a transmission component, a receivercomponent, and a processor. The transmission component is configured toprovide capability information to an eNB indicating that the UE is notcapable of simultaneous transmission or reception of additional signalswhile receiving reference signals. The receiver component is configuredto receive a measurement gap pattern from the eNB. The measurement gappattern includes a measurement gap. The processor configures, based onthe measurement gap pattern, the UE to perform proximity detectionmeasurement on one or more reference signals during the measurement gap.The processor configures the UE to prohibit transmission or reception ofadditional signals during the measurement gap.

In Example 18, the measurement gap of the measurement gap pattern ofExample 17 can optionally occur on a period greater than a cellreference signal.

In Example 19, the measurement gap of Examples 17-18 can optionally beshared with one or more of inter-frequency measurement and inter-RATmeasurement.

In Example 20, the receiver component of Examples 17-19 can optionallyfurther receive prioritization information to prioritize one or more ofthe proximity detection measurement, the inter-frequency measurement,and the inter-RAT measurement to be performed first by the UE.

Example 21 is a method for proximity detection. The method includesproviding a measurement capability enquiry to a UE. The method includesreceiving measurement capability information from the UE. Themeasurement capability information indicates whether the UE is capableof simultaneous transmission and reception of UL signals. The methodincludes providing proximity detection measurement configurationinformation for configuring proximity detection and reporting at the UEbased on the proximity detection measurement configuration information.The measurement configuration information includes one or more of ameasurement gap pattern, radio resource configuration information for areference signal, an event definition, and a reporting interval. Themethod includes receiving measurement reports from the UE regarding oneor more reference signals measured by the UE.

In Example 22, the method of Example 21 can optionally further includeconfiguring D2D communication between the UE and one or more devicescorresponding to the one or more PD-RSs based on the receivedmeasurement reports.

In Example 23, configuring D2D communication of Examples 21-22 canoptionally include one or more of establishing D2D communication,modifying D2D communication, and ending D2D communication between the UEand the one or more devices.

Example 24, is an eNB that includes processing circuitry. The processingcircuitry maintains a reference signal list on a mobile station. Thereference signal list includes radio resource configurations for one ormore reference signals. The processing circuitry receives measurementreports from the mobile station regarding at least one reference signalof the one or more reference signals on the reference signal listmeasured by the mobile station. The processing circuitry configures D2Dcommunication between the mobile station and one or more devicescorresponding to the one or more reference signals based on the receivedmeasurement reports.

In Example 25, configuring D2D communication in Example 24 optionallyincludes one or more of establishing D2D communication, modifying D2Dcommunication, and ending D2D communication between the mobile stationand the one or more devices.

Example 26 is a method for proximity detection. The method includesreceiving and storing a PD-RS list from an eNB, the PD-RS listcomprising a radio resource configuration for at least a first (PD-RS).The method includes measuring at least the first PD-RS to determine asignal parameter for the first PD-RS. The method includes reporting thesignal parameter for the first PD-RS to the eNB.

In Example 27, the radio resource configuration for the first PD-RS ofExample 26 can optionally include a transmission offset. Thetransmission offset indicates a transmission power of the first PD-RS.

In Example 28, the radio resource configuration for the first PD-RS ofExamples 26-27 can optionally include an identifier for the first PD-RS.

In Example 29, the method of Examples 26-28 can optionally includereceiving an open discovery mode configuration. The open discovery modeconfiguration configures the UE to measure any PD-RS in addition to thePD-RSs listed in the PD-RS list.

In Example 30, the method of Examples 26-29 can optionally includereceiving a restricted discovery mode configuration. The restricteddiscovery mode configuration configures the UE to only measure PD-RSslisted in the PD-RS list.

In Example 31, the receiving and storing the PD-RS list of Examples26-30 can optionally include receiving a PD-RS addition messageincluding the radio resource configuration for the first PD-RS andstoring the radio resource configuration in the PD-RS list.

In Example 32, the receiving and storing the PD-RS list of Examples26-31 can optionally include receiving a PD-RS replacement messageincluding the radio resource configuration for the first PD-RS andstoring the radio resource configuration in the PD-RS list to replaceprevious radio resource configuration information.

In Example 33, the method of Examples 26-32 can optionally includereceiving a PD-RS removal message indicating removal of an entry for asecond PD-RS and removing the entry for the second PD-RS from the PD-RSlist in response to receiving the PD-RS removal message.

In Example 34, a PD-RS removal message of Example 33 optionally includesan index for the entry for the second PD-RS.

In Example 35, the methods of Examples 26-34 can optionally includereceiving at least one of a measurement gap pattern, an eventdefinition, and/or a reporting interval.

In Example 36, an apparatus optionally includes means to perform an ofthe methods of Examples 26-35.

Example 37 is a UE that includes a receiver component, a processor, anda transmission component. The receiver component is configured toreceive, from an eNB, measurement report configuration data comprisingan event definition. The receiver component is configured to measure areference signal to determine a signal parameter for the referencesignal. The signal parameter for the reference signal includes a signalstrength of the reference signal. The processor is configured to detectan event based on the signal parameter for the reference signal and theevent definition. The event indicates a change in the signal parameterfor the reference signal. The transmission component is configured toreport, in response to detecting the event, the signal parameter for thereference signal to the eNB.

In Example 38, the event definition of Example 38 can optionally defineoccurrence the signal parameter for the reference signal exceeding anabsolute threshold.

In Example 39, the event definition of Examples 37-38 can optionallydefine occurrence of the signal parameter for the reference signalfalling below an absolute threshold when a device corresponding to thereference signal is in D2D communication with the UE.

In Example 40, the event definition of Examples 37-39 can optionallydefine occurrence of a first signal parameter for the reference signalimproving above a second signal parameter for a reference signal of adevice that is a member of a D2D group comprising the UE.

In Example 41, the event definition of Examples 37-40 can optionallydefine occurrence of the signal parameter for the reference signal andone or more additional reference signal exceeding an absolute threshold.

In Example 42, the processor of Examples 37-41 can optionally beconfigured to determine that the reference signal corresponds to adevice that is engaged in D2D communication with the UE.

In Example 43, the measurement report configuration data received by thereceiver component of Examples 37-42 optionally includes a reportinginterval.

In Example 44, the measurement report configuration data of Examples37-43 optionally configures the transmission component to provide ameasurement report to the eNB periodically on the reporting intervalregardless of whether the event is detected.

In Example 44, the measurement report configuration data of Examples37-43 optionally configures the transmission component to provide ameasurement report to the eNB periodically on the reporting interval inresponse to detecting the event.

Example 45 is machine readable storage including machine-readableinstructions, when executed, to implement a method or realize anapparatus of any of Examples 1-44.

Those having skill in the art will appreciate that many changes may bemade to the details of the above-described embodiments without departingfrom the underlying principles of the disclosure. The scope of thepresent disclosure should, therefore, be determined only by thefollowing claims.

1. User equipment (UE) comprising processing circuitry configured to:receive and store a proximity discovery reference signal (PD-RS) listfrom an evolved universal terrestrial radio access network (E-UTRAN)node B (eNB), the PD-RS list comprising a radio resource configurationfor at least a first PD-RS; measure at least the first PD-RS todetermine a signal parameter for the first PD-RS; and report the signalparameter for the first PD-RS to the eNB.
 2. The UE of claim 1, whereinthe radio resource configuration for the first PD-RS comprises atransmission offset, the transmission offset indicating a transmissionpower of the first PD-RS.
 3. The UE of claim 1, wherein the radioresource configuration for the first PD-RS comprises an identifier forthe first PD-RS.
 4. The UE of claim 1, wherein the processing circuitryis further configured to receive an open discovery mode configuration,wherein the open discovery mode configuration configures the UE tomeasure any PD-RS in addition to the PD-RSs listed in the PD-RS list. 5.The UE of claim 1, wherein the processing circuitry is furtherconfigured to receive a restricted discovery mode configuration, whereinthe restricted discovery mode configuration configures the UE to onlymeasure PD-RSs listed in the PD-RS list.
 6. The UE of claim 1, whereinreceiving and storing the PD-RS list comprises receiving a PD-RSaddition message comprising the radio resource configuration for thefirst PD-RS and storing the radio resource configuration in the PD-RSlist.
 7. The UE of claim 1, wherein receiving and storing the PD-RS listcomprises receiving a PD-RS replacement message comprising the radioresource configuration for the first PD-RS and storing the radioresource configuration in the PD-RS list to replace previous radioresource configuration information.
 8. The UE of claim 1, wherein theprocessing circuitry is further configured to receive a PD-RS removalmessage indicating removal of an entry for a second PD-RS and remove theentry for the second PD-RS from the PD-RS list in response to receivingthe PD-RS removal message.
 9. The UE of claim 7, wherein the PD-RSremoval message comprises an index for the entry for the second PD-RS.10. User equipment (UE) comprising: a receiver component configured toreceive, from an evolved universal terrestrial radio access network(E-UTRAN) node B (eNB), measurement report configuration data comprisingan event definition, and measure a reference signal to determine asignal parameter for the reference signal, the signal parameter for thereference signal comprising a signal strength of the reference signal; aprocessor configured to detect an event based on the signal parameterfor the reference signal and the event definition, the event indicatinga change in the signal parameter for the reference signal; and atransmission component configured to report, in response to detectingthe event, the signal parameter for the reference signal to the eNB. 11.The UE of claim 10, wherein the event definition defines occurrence ofthe signal parameter for the reference signal exceeding an absolutethreshold.
 12. The UE of claim 10, wherein the event definition definesoccurrence of the signal parameter for the reference signal fallingbelow an absolute threshold when a device corresponding to the referencesignal is in device-to-device (D2D) communication with the UE.
 13. TheUE of claim 10, wherein the event definition defines occurrence of afirst signal parameter for the reference signal improving above a secondsignal parameter for a reference signal of a device that is a member ofa D2D group comprising the UE.
 14. The UE of claim 10, wherein the eventdefinition defines occurrence of the signal parameter for the referencesignal and one or more additional reference signal exceeding an absolutethreshold.
 15. The UE of claim 10, wherein the processor is furtherconfigured to determine that the reference signal corresponds to adevice that is engaged in D2D communication with the UE.
 16. The UE ofclaim 10, wherein the measurement report configuration data received bythe receiver component further comprises a reporting interval andwherein the measurement report configuration data configures thetransmission component to provide a measurement report to the eNB one ormore of: periodically on the reporting interval regardless of whetherthe event is detected; and periodically on the reporting interval inresponse to detecting the event.
 17. User equipment (UE) comprising: atransmission component configured to provide capability information toan evolved universal terrestrial radio access network (E-UTRAN) node B(eNB) indicating that the UE is not capable of simultaneous transmissionor reception of additional signals while receiving reference signals; areceiver component configured to receive a measurement gap pattern fromthe eNB, the measurement gap pattern comprising a measurement gap; and aprocessor to configure, based on the measurement gap pattern, the UE toperform proximity detection measurement on one or more reference signalsduring the measurement gap, and to prohibit transmission or reception ofadditional signals during the measurement gap.
 18. The UE of claim 17,wherein the measurement gap of the measurement gap pattern occurs on aperiod greater than a cell reference signal.
 19. The UE of claim 17,wherein the measurement gap is shared with one or more ofinter-frequency measurement and inter-radio access technology (RAT)measurement.
 20. The UE of claim 19, wherein the receiver componentfurther receives prioritization information to prioritize one or more ofthe proximity detection measurement, the inter-frequency measurement,and the inter-RAT measurement to be performed first by the UE.
 21. Amethod for proximity detection, the method comprising: providing ameasurement capability enquiry to user equipment (UE); receivingmeasurement capability information from the UE, the measurementcapability information indicating whether the UE is capable ofsimultaneous transmission and reception of uplink (UL) signals;providing proximity detection measurement configuration information forconfiguring proximity detection and reporting at the UE based on theproximity detection measurement configuration information, themeasurement configuration information comprising one or more of ameasurement gap pattern, radio resource configuration information for areference signal, an event definition, and a reporting interval; andreceiving measurement reports from the UE regarding one or morereference signals measured by the UE.
 22. The method of claim 21, themethod further comprising configuring device-to-device (D2D)communication between the UE and one or more devices corresponding tothe one or more PD-RSs based on the received measurement reports. 23.The method of claim 22, wherein configuring D2D communication comprisesone or more of establishing D2D communication, modifying D2Dcommunication, and ending D2D communication between the UE and the oneor more devices.